The invention relates to a method of operating a crane having a movable undercarriage and a superstructure rotatably supported thereon with a luffable main boom and derrick boom arranged thereon.
Large cranes, in particular large crawler-mounted cranes, require a considerable counter-weight which counteracts the raised payload and prevents the tilting of the crane. This counter-weight can be applied by a central ballast, by a superstructure ballast or also by a ballast at the derrick boom. As a rule, a ballast plate supported with respect to the ground via corresponding auxiliary means to take up the ballast is proposed as a possible derrick ballast. A completely suspended ballast or also a derrick ballast carried by a ballast box is possible as an alternative.
Against this background special ballast boxes have been developed which are designed as independently driven vehicles and can therefore be moved together with the crane to ensure a largely unrestricted crane operation. Such solutions, however, always require a complex separate development of a suitable ballast box which is used only for the ballast application. Furthermore, such a ballast box has to be transported separately onto the construction site for the crane use, which his a disadvantegeous effect on the deployment costs incurred since they depend as a rule on the required ballast mass.
A further problem for the dimensioning at the required ballast presents itself on the erecting of long boom combinations. The boom disposed on the ground has a comparatively are lever arm and therefore induces a comparatively large load torque which far exceeds the load torques occurring later during the crane operation. DE 203 14 503 U1 therefore suggests as a solution to bypass this problem to arrange the auxiliary crane required for the equipping process as additional ballast at the superstructure of the crane to be able to compensate the load torques arising during the erection procedure. It is, however, disadvantageous proposed method that the auxiliary crane operating as ballast can only be used during the erection since it would greatly impair the freedom of movement of the crane during the crane work.